Avoid slow read-back from VRAM.

* include/grub/video_fb.h (grub_video_fb_doublebuf_update_screen_t):
	Move from here ...
	* grub-core/video/fb/video_fb.c
	(grub_video_fb_doublebuf_update_screen_t): ... here. Remove arguments.
	* grub-core/video/fb/video_fb.c (framebuf_t): New type.
	(front_target): Remove front_target. Add pages.
	(grub_video_fb_init): Skip setting front_pages.
	(grub_video_fb_fini): Likewise.
	(doublebuf_blit_update_screen): Use pages.
	(grub_video_fb_doublebuf_blit_init): Likewise.
	(doublebuf_pageflipping_init): Allocate offscreen buffer.
	(doublebuf_pageflipping_update_screen): Use offscreen buffer.
	(grub_video_fb_setup): Prefer doublebuffing.

ChangeLog

@@ -1,3 +1,21 @@
+2012-06-15  Vladimir Serbinenko  <phcoder@gmail.com>
+
+	Avoid slow read-back from VRAM.
+
+	* include/grub/video_fb.h (grub_video_fb_doublebuf_update_screen_t):
+	Move from here ...
+	* grub-core/video/fb/video_fb.c
+	(grub_video_fb_doublebuf_update_screen_t): ... here. Remove arguments.
+	* grub-core/video/fb/video_fb.c (framebuf_t): New type.
+	(front_target): Remove front_target. Add pages.
+	(grub_video_fb_init): Skip setting front_pages.
+	(grub_video_fb_fini): Likewise.
+	(doublebuf_blit_update_screen): Use pages.
+	(grub_video_fb_doublebuf_blit_init): Likewise.
+	(doublebuf_pageflipping_init): Allocate offscreen buffer.
+	(doublebuf_pageflipping_update_screen): Use offscreen buffer.
+	(grub_video_fb_setup): Prefer doublebuffing.
+
 2012-06-15  Vladimir Serbinenko  <phcoder@gmail.com>
 
 	* grub-core/normal/main.c (GRUB_MOD_INIT): Ignore errors when loading

grub-core/video/fb/video_fb.c

@@ -28,12 +28,15 @@
 
 GRUB_MOD_LICENSE ("GPLv3+");
 
+typedef grub_err_t (*grub_video_fb_doublebuf_update_screen_t) (void);
+typedef volatile void *framebuf_t;
+
 static struct
 {
   struct grub_video_fbrender_target *render_target;
-  struct grub_video_fbrender_target *front_target;
   struct grub_video_fbrender_target *back_target;
   struct grub_video_palette_data *palette;
+  framebuf_t pages[2];
   unsigned int palette_size;
   /* For page flipping strategy.  */
   int displayed_page;           /* The page # that is the front buffer.  */
@@ -72,7 +75,6 @@ grub_video_fb_init (void)
 {
   grub_free (framebuffer.palette);
   framebuffer.render_target = 0;
-  framebuffer.front_target = 0;
   framebuffer.back_target = 0;
   framebuffer.palette = 0;
   framebuffer.palette_size = 0;
@@ -88,7 +90,6 @@ grub_video_fb_fini (void)
   grub_free (framebuffer.offscreen_buffer);
   grub_free (framebuffer.palette);
   framebuffer.render_target = 0;
-  framebuffer.front_target = 0;
   framebuffer.back_target = 0;
   framebuffer.palette = 0;
   framebuffer.palette_size = 0;
@@ -1283,64 +1284,57 @@ grub_video_fb_get_active_render_target (struct grub_video_fbrender_target **targ
 }
 
 static grub_err_t
-doublebuf_blit_update_screen (struct grub_video_fbrender_target *front,
+doublebuf_blit_update_screen (void)
-			      struct grub_video_fbrender_target *back)
 {
-  grub_memcpy (front->data, back->data,
+  grub_memcpy ((void *) framebuffer.pages[0], framebuffer.back_target->data,
-	       front->mode_info.pitch * front->mode_info.height);
+	       framebuffer.back_target->mode_info.pitch
+	       * framebuffer.back_target->mode_info.height);
   return GRUB_ERR_NONE;
 }
 
 static grub_err_t
-grub_video_fb_doublebuf_blit_init (struct grub_video_fbrender_target **front,
+grub_video_fb_doublebuf_blit_init (struct grub_video_fbrender_target **back,
-				   struct grub_video_fbrender_target **back,
 				   struct grub_video_mode_info mode_info,
-				   void *framebuf)
+				   volatile void *framebuf)
 {
   grub_err_t err;
-  int page_size = mode_info.pitch * mode_info.height;
+  grub_size_t page_size = mode_info.pitch * mode_info.height;
-
-  err = grub_video_fb_create_render_target_from_pointer (front, &mode_info,
-							 framebuf);
-  if (err)
-    return err;
 
   framebuffer.offscreen_buffer = grub_malloc (page_size);
   if (! framebuffer.offscreen_buffer)
-    {
+    return grub_errno;
-      grub_video_fb_delete_render_target (*front);
-      *front = 0;
-      return grub_errno;
-    }
 
-  err = grub_video_fb_create_render_target_from_pointer (back, &mode_info,
+  err = grub_video_fb_create_render_target_from_pointer (&framebuffer.back_target,
+							 &mode_info,
 							 framebuffer.offscreen_buffer);
 
   if (err)
     {
-      grub_video_fb_delete_render_target (*front);
       grub_free (framebuffer.offscreen_buffer);
       framebuffer.offscreen_buffer = 0;
-      *front = 0;
       return grub_errno;
     }
   (*back)->is_allocated = 1;
 
   framebuffer.update_screen = doublebuf_blit_update_screen;
+  framebuffer.pages[0] = framebuf;
+  framebuffer.displayed_page = 0;
+  framebuffer.render_page = 0;
 
   return GRUB_ERR_NONE;
 }
 
 static grub_err_t
-doublebuf_pageflipping_update_screen (struct grub_video_fbrender_target *front
+doublebuf_pageflipping_update_screen (void)
-				      __attribute__ ((unused)),
-				      struct grub_video_fbrender_target *back
-				      __attribute__ ((unused)))
 {
   int new_displayed_page;
-  struct grub_video_fbrender_target *target;
   grub_err_t err;
 
+  grub_memcpy ((void *) framebuffer.pages[framebuffer.render_page],
+	       framebuffer.back_target->data,
+	       framebuffer.back_target->mode_info.pitch
+	       * framebuffer.back_target->mode_info.height);
+
   /* Swap the page numbers in the framebuffer struct.  */
   new_displayed_page = framebuffer.render_page;
   framebuffer.render_page = framebuffer.displayed_page;
@@ -1355,26 +1349,7 @@ doublebuf_pageflipping_update_screen (struct grub_video_fbrender_target *front
       return err;
     }
 
-  target = framebuffer.back_target;
+  return GRUB_ERR_NONE;
-  framebuffer.back_target = framebuffer.front_target;
-  framebuffer.front_target = target;
-
-  if (framebuffer.front_target->mode_info.mode_type
-      & GRUB_VIDEO_MODE_TYPE_UPDATING_SWAP)
-    grub_memcpy (framebuffer.back_target->data, framebuffer.front_target->data,
-		 framebuffer.back_target->mode_info.pitch
-		 * framebuffer.back_target->mode_info.height);
-
-  err = grub_video_fb_get_active_render_target (&target);
-  if (err)
-    return err;
-
-  if (framebuffer.render_target == framebuffer.back_target)
-    framebuffer.render_target = framebuffer.front_target;
-  else if (framebuffer.render_target == framebuffer.front_target)
-    framebuffer.render_target = framebuffer.back_target;
-
-  return err;
 }
 
 static grub_err_t
@@ -1384,32 +1359,37 @@ doublebuf_pageflipping_init (struct grub_video_mode_info *mode_info,
 			     volatile void *page1_ptr)
 {
   grub_err_t err;
+  grub_size_t page_size = mode_info->pitch * mode_info->height;
+
+  framebuffer.offscreen_buffer = grub_malloc (page_size);
+  if (! framebuffer.offscreen_buffer)
+    {
+      return grub_errno;
+    }
+
+  err = grub_video_fb_create_render_target_from_pointer (&framebuffer.back_target,
+							 mode_info,
+							 framebuffer.offscreen_buffer);
+
+  if (err)
+    {
+      grub_free (framebuffer.offscreen_buffer);
+      framebuffer.offscreen_buffer = 0;
+      return grub_errno;
+    }
+  framebuffer.back_target->is_allocated = 1;
 
   framebuffer.displayed_page = 0;
   framebuffer.render_page = 1;
 
   framebuffer.update_screen = doublebuf_pageflipping_update_screen;
-
+  framebuffer.pages[0] = page0_ptr;
-  err = grub_video_fb_create_render_target_from_pointer (&framebuffer.front_target,
+  framebuffer.pages[1] = page1_ptr;
-							 mode_info,
-							 (void *) page0_ptr);
-  if (err)
-    return err;
-
-  err = grub_video_fb_create_render_target_from_pointer (&framebuffer.back_target,
-							 mode_info,
-							 (void *) page1_ptr);
-  if (err)
-    {
-      grub_video_fb_delete_render_target (framebuffer.front_target);
-      return err;
-    }
 
   /* Set the framebuffer memory data pointer and display the right page.  */
   err = set_page_in (framebuffer.displayed_page);
   if (err)
     {
-      grub_video_fb_delete_render_target (framebuffer.front_target);
       grub_video_fb_delete_render_target (framebuffer.back_target);
       return err;
     }
@@ -1427,20 +1407,14 @@ grub_video_fb_setup (unsigned int mode_type, unsigned int mode_mask,
 		     volatile void *page1_ptr)
 {
   grub_err_t err;
-  int updating_swap_needed;
-
-  updating_swap_needed
-    = grub_video_check_mode_flag (mode_type, mode_mask,
-				  GRUB_VIDEO_MODE_TYPE_UPDATING_SWAP, 0);
 
   /* Do double buffering only if it's either requested or efficient.  */
   if (set_page_in && grub_video_check_mode_flag (mode_type, mode_mask,
 						 GRUB_VIDEO_MODE_TYPE_DOUBLE_BUFFERED,
-						 !updating_swap_needed))
+						 1))
     {
       mode_info->mode_type |= GRUB_VIDEO_MODE_TYPE_DOUBLE_BUFFERED;
-      if (updating_swap_needed)
+      mode_info->mode_type |= GRUB_VIDEO_MODE_TYPE_UPDATING_SWAP;
-	mode_info->mode_type |= GRUB_VIDEO_MODE_TYPE_UPDATING_SWAP;
 
       err = doublebuf_pageflipping_init (mode_info, page0_ptr,
 					 set_page_in,
@@ -1459,7 +1433,7 @@ grub_video_fb_setup (unsigned int mode_type, unsigned int mode_mask,
 
   if (grub_video_check_mode_flag (mode_type, mode_mask,
 				  GRUB_VIDEO_MODE_TYPE_DOUBLE_BUFFERED,
-				  0))
+				  1))
     {
       /* It was much nicer with the cast directly at function call but
 	 some older gcc versions don't accept it properly.*/
@@ -1467,8 +1441,7 @@ grub_video_fb_setup (unsigned int mode_type, unsigned int mode_mask,
       mode_info->mode_type |= (GRUB_VIDEO_MODE_TYPE_DOUBLE_BUFFERED
 			       | GRUB_VIDEO_MODE_TYPE_UPDATING_SWAP);
 
-      err = grub_video_fb_doublebuf_blit_init (&framebuffer.front_target,
+      err = grub_video_fb_doublebuf_blit_init (&framebuffer.back_target,
-					       &framebuffer.back_target,
 					       *mode_info,
 					       tmp);
 
@@ -1485,15 +1458,18 @@ grub_video_fb_setup (unsigned int mode_type, unsigned int mode_mask,
     }
 
   /* Fall back to no double buffering.  */
-  err = grub_video_fb_create_render_target_from_pointer (&framebuffer.front_target,
+  err = grub_video_fb_create_render_target_from_pointer (&framebuffer.back_target,
 							 mode_info,
 							 (void *) page0_ptr);
 
   if (err)
     return err;
 
-  framebuffer.back_target = framebuffer.front_target;
   framebuffer.update_screen = 0;
+  framebuffer.pages[0] = page0_ptr;
+  framebuffer.displayed_page = 0;
+  framebuffer.render_page = 0;
+  framebuffer.set_page = 0;
 
   mode_info->mode_type &= ~GRUB_VIDEO_MODE_TYPE_DOUBLE_BUFFERED;
 
@@ -1510,8 +1486,7 @@ grub_video_fb_swap_buffers (void)
   if (!framebuffer.update_screen)
     return GRUB_ERR_NONE;
 
-  err = framebuffer.update_screen (framebuffer.front_target,
+  err = framebuffer.update_screen ();
-				   framebuffer.back_target);
   if (err)
     return err;
 
@@ -1522,23 +1497,17 @@ grub_err_t
 grub_video_fb_get_info_and_fini (struct grub_video_mode_info *mode_info,
 				 void **framebuf)
 {
-  grub_memcpy (mode_info, &(framebuffer.front_target->mode_info),
+  grub_memcpy (mode_info, &(framebuffer.back_target->mode_info),
 	       sizeof (*mode_info));
 
   /* We are about to load a kernel.  Switch back to page zero, since some
      kernel drivers expect that.  */
-  if ((mode_info->mode_type & GRUB_VIDEO_MODE_TYPE_DOUBLE_BUFFERED)
+  if (framebuffer.set_page && framebuffer.displayed_page != 0)
-      && framebuffer.set_page && framebuffer.displayed_page != 0)
     {
-      /* Ensure both pages are exactly in sync.  */
+      framebuffer.update_screen ();
-      grub_memcpy (framebuffer.back_target->data,
-		   framebuffer.front_target->data,
-		   framebuffer.back_target->mode_info.pitch
-		   * framebuffer.back_target->mode_info.height);
-      grub_video_swap_buffers ();
     }
 
-  *framebuf = framebuffer.front_target->data;
+  *framebuf = (void *) framebuffer.pages[framebuffer.displayed_page];
 
   grub_video_fb_fini ();
 

grub-core/video/ieee1275.c

@@ -40,7 +40,6 @@ static int have_setcolors = 0;
 static struct
 {
   struct grub_video_mode_info mode_info;
-  struct grub_video_render_target *render_target;
   grub_uint8_t *ptr;
 } framebuffer;
 
@@ -186,23 +185,12 @@ grub_video_ieee1275_setup (unsigned int width, unsigned int height,
   grub_dprintf ("video", "IEEE1275: initialising FB @ %p %dx%dx%d\n",
 		framebuffer.ptr, framebuffer.mode_info.width,
 		framebuffer.mode_info.height, framebuffer.mode_info.bpp);
-  
-  err = grub_video_fb_create_render_target_from_pointer 
-    (&framebuffer.render_target, &framebuffer.mode_info, framebuffer.ptr);
 
+  err = grub_video_fb_setup (mode_type, mode_mask,
+			     &framebuffer.mode_info,
+			     framebuffer.ptr, NULL, NULL);
   if (err)
-    {
+    return err;
-      grub_dprintf ("video", "IEEE1275: Couldn't create FB target\n");
-      return err;
-    }
-  
-  err = grub_video_fb_set_active_render_target (framebuffer.render_target);
-  
-  if (err)
-    {
-      grub_dprintf ("video", "IEEE1275: Couldn't set FB target\n");
-      return err;
-    }
 
   grub_video_ieee1275_set_palette (0, GRUB_VIDEO_FBSTD_NUMCOLORS,
 				   grub_video_fbstd_colors);
@@ -210,22 +198,6 @@ grub_video_ieee1275_setup (unsigned int width, unsigned int height,
   return err;
 }
 
-static grub_err_t
-grub_video_ieee1275_swap_buffers (void)
-{
-  /* TODO: Implement buffer swapping.  */
-  return GRUB_ERR_NONE;
-}
-
-static grub_err_t
-grub_video_ieee1275_set_active_render_target (struct grub_video_render_target *target)
-{
-  if (target == GRUB_VIDEO_RENDER_TARGET_DISPLAY)
-    target = framebuffer.render_target;
-
-  return grub_video_fb_set_active_render_target (target);
-}
-
 static grub_err_t
 grub_video_ieee1275_get_info_and_fini (struct grub_video_mode_info *mode_info,
 				  void **framebuf)
@@ -287,10 +259,10 @@ static struct grub_video_adapter grub_video_ieee1275_adapter =
     .blit_bitmap = grub_video_fb_blit_bitmap,
     .blit_render_target = grub_video_fb_blit_render_target,
     .scroll = grub_video_fb_scroll,
-    .swap_buffers = grub_video_ieee1275_swap_buffers,
+    .swap_buffers = grub_video_fb_swap_buffers,
     .create_render_target = grub_video_fb_create_render_target,
     .delete_render_target = grub_video_fb_delete_render_target,
-    .set_active_render_target = grub_video_ieee1275_set_active_render_target,
+    .set_active_render_target = grub_video_fb_set_active_render_target,
     .get_active_render_target = grub_video_fb_get_active_render_target,
 
     .next = 0

include/grub/video_fb.h

@@ -115,10 +115,6 @@ grub_video_fb_get_active_render_target (struct grub_video_fbrender_target **targ
 grub_err_t
 grub_video_fb_set_active_render_target (struct grub_video_fbrender_target *target);
 
-typedef grub_err_t
-(*grub_video_fb_doublebuf_update_screen_t) (struct grub_video_fbrender_target *front,
-					  struct grub_video_fbrender_target *back);
-
 typedef grub_err_t (*grub_video_fb_set_page_t) (int page);
 
 grub_err_t